Signal instrument



May 22, 1934. P HAASIS 1,959,470

l SIGNAL INSTRUMENT Filed Aug. 13, 1930 Patented May Z2, 1934 UNITED STATES 1,959,470 ASIGNAL INSTRUMENT Paul Haasis, Zuifenhausen, Germany `Application `August 13', 1930, Serial No. 475,110

In Germany January 21, 1930 7 Claims. (Cl. f77-J7) The present inventionrelates to signal instruments, in which a diaphragm is caused electromagnetically to carrying out sound-producing vibrations. y

The prior art knows electromagnetically actuated signal instruments, in whichthe diaphragm is fixed only to parts of the edge or near the edge, and wherein the break Contact aswell as the armature are arranged directly on the diaphragm.

It is further known to bring about the vibration of the fixed diaphragm merely by means of one attracting pole and one coil, but the existing kinds of instruments of this class are composed of numerous parts, expensive to produce, unreliable in operation and only in very few cases capable of transmitting loud and clear sounds.

The present inventionprovides a signal instrument which consists only of a few parts toreduce production cost and increase safety in operation and which is nevertheless highly efficient in sound production. This instrument can be used ior both low pressure and power current.

It has been found to be in the interest of simple and cheap production to let the diaphragm itself act as suitable tension spring for the break contact attached to the diaphragm in such a way that this tension is directly dependent on the position and movement of the armature. The break contact screw is carried by an iron guide secured to the outer pole member and holding at the same time the diaphragm. The point-like attachment of the diaphragm to the outer Shanks of the magnet system permits deflection of the diaphragm within widest limlts, and thus maximum sound production. The sound is conducted through recesses in the lower edge of the instru ment base to the wall from which the instrument is suspended. To save material and insure greatest lightness, the iron pedestal of the instrument with the two outer shanks of the magnet system is constructed so that the portion receiving the coils is disposed in the hollow base to reduce the height of the instrument. The covering protective cap has holes which elastically snap into position if brought into contact with corresponding elevations, noses and the like at the lower edge.

The invention is illustrated by way of example in the accompanying drawing, in which Figure 1 is a top View of a device embodying the invention; Fig. 2, a side View thereof; Fig. 3, a section of the armature on the line C-D; and Figs. 4 and 5 are two Vertical sections of the signal instrument.

Referring to the drawing, the diaphragm a may be of any desired shape and is circular in this case. It is'xed at h-b` to the shanks c of the pedestal or base of the instrument so thatthe fixing points are very small relative tothe surface of the diaphragm and the latter may carry out sound-producing vibrations almost over its entire area. The fastening points maybe varied in size to hold the diaphragm more securely or ind order to vary its rate of vibration. It is essential that the remaining free portion of the diaphragm G can vibrate without interference between C and D. The sound or rather the number of Vibrations produced by the instrument depends on the diam,- et-er and strength of the diaphragm, the weight of the armature, and the manner of fixing. If a larger diaphragm is used, it may be secured to several points; for instance, to two points arranged separately from one another oneach'pole member.

The armature d is secured to the diaphragm in any suitable manner, though it is essential ,that the armature be positioned between the i-lxingv points b-b at rightl angles or any other angle transversely to the axis of symmetryV or oscillation curve A-B and be secured to, and resting on, two or more points located as farv as possible fromone another, the size of the angle influencing the frate of vibration and thereby the pitch. The armature may have the form of a flat rectangle or be of a crossfiike, circular or other shape. In Fig. 3 it is off-set, butV the necessary distance between the armature and the diaphragm can be provided also by intermediate plates.

The pitch and intensity of the tone depend not only on the thickness of the diaphragm, but also to a considerable degree on the distance of the bearing points ofthe armature d, which, in the example shown, is almost equal to the diameter of the diaphragm. If the distance between the armature fastening points is reduced, the number of natural vibrations of this portion of the diaphragmvwill be increased and the sound produced have a higher pitch. It is important for the usefulness of the armature that its fastening points are disposed preferably in the plane of symmetry or in its neighborhood to insure the best possible vibration of the diaphragm, and that the armature is distant enough to allow deflection of the diaphragm. To improve the magnetic flux of the narrow armature d, which might be very thin to save weight, the iron guide f is secured to the outer pole members and thus to the diaphragm which closes the magnetic field and carries the break contact screw. Owing to its slight distance from the armature and the diaphragm, this iron guide favors essentially the magnetic eld of the armature towards the outer pole members.v The pedestal h is made of iron and preferably integral with the outer pole members c orl it can be constructed so that the outer pole members are secured to base drawn from sheet iron. The core z' of the magnet made vof soft iron free from remanence is specially secured to the base. In the bottom of the instrument base the sound holes lc are provided through which the sound produced by the diaphragm is guided to the wall to which the instrument is secured and then passed into the open through the free space between the instrument base and the wall. By freely suspending the instrument base from the Wall better vibration and transmission of the the instrument the portion of the pedestal receiving the coil Z is sunk into the hollow base. The instrument is protected against dust and other influences by aremovable cap m provided with a handle, which can be constructed so as to snap elastically into the rivet heads n or othery elevations provided at the outer pole members, the engagement being effected by the holes at the lower edge of the cap. rAn instrument base made -as described, for instance as a casting, ycan be produced at low cost owing to the reduction in the number of parts required and the considerable reduction in weight by recesses, sound holes, etc. It is hardly possible that the instrument should get dusty owing to the presence of Athe sound holes, since the base is secured near the wall.

I claim:

1. An electromagnetic sound-producing device comprising a base member; a diaphragm fixed to the base at two opposite points thereof; an armature xed to the diaphragm at two opposite points thereon, said armature fastening points being positioned relative to the diaphragm fastening vpoints in such manner that a line through the armature fastening poi-nts is substantially at right angles to a line through the diaphragm fastening points, and electro-magnetic means for actuating the armature.

`according to claim 1 in which sound waves to` the wall are attained. To reduce the length of' 2. An electromagnetic sound-producing device the armature is provided with means at the ends thereof at the points bearing on the diaphragm to space the armature from the diaphragm.

3. An electromagnetic sound-producing device according to claim 1 including intermediate members adapted to space the armature relative to the diaphragm.

4. An electromagnetic sound-producing device according to claim 1 in which the means for actuating the armature includes a three-armed magnet and the diaphragm is secured to the two outer arms.

5. An electromagnetic sound-producing device according to claim 1 in which the means for actuating the varmature includes a three-armed magnet and the diaphragm is secured to the two outer arms, and an iron member is provided for bridging the two outer arms.

6. A sound producing device comprising a base portion; a diaphragm fixed to the base portion at two opposite points thereof so that the diaphragm may vibrate between these points; a member xed to the diaphragm at two opposite points thereon so that the diaphragm may also vibrate between-these twopoints, a -line connecting the two points of the diaphragm connection to the baseportion Ibeing in angular relationship with a line connecting the two points of the member connection to the diaphragm; and means for vibratingthe member.

7.V An electromagnetic sound-producing device, comprising a base member; a diaphragm xed to the base member at two opposite points thereof so that the diaphragm may vibrate between these points; an armature xed to the diaphragm at two opposite points thereon so that the diaphragm may also vibrate between these two points, a line `connecting the two points of the diaphragm connection to the base member being in angular relationship with a line connecting the twopoints of the armature connection to the diaphragm; and electromagnetic means for actuating the armature.

- PAUL HAASIS. 

